Monopolar devices have been employed for years to cauterize vessels and cut tissue depending on the frequency used. Monopolar devices operate by using the patient as the ground pathway to complete the circuit. However, this arrangement is not efficacious in certain applications, such as neurosurgical procedures, as the energy moves through the entire body, including, for example, brain tissue.
Bipolar cautery devices have also been employed to coagulate and cauterize tissues such as vessels. Bipolar cautery devices utilize two electrodes, with the intent to localize energy between the two poles of the electrodes, thereby minimizing energy delivery to adjacent tissues and structures. However, one of the issues with bipolar cautery devices is the ability to control the amount of energy to be delivered to accomplish the desired coagulation or tissue welding, depending on the application. Less energy is required the closer the electrodes are positioned together. However, it is undesirable to have the electrodes contact each other directly, as when this happens, no energy is being delivered to the intended tissues and no coagulation/cautery occurs to the intended tissue. If the electrodes are spaced too far apart, more energy is required to achieve coagulation, which can lead to collateral tissue damage.
In certain applications, such as in neurosurgical applications, it is desirable to deliver as low an amount of energy as possible when attempting to mitigate a bleeding vessel to prevent collateral tissue damage, especially around critical structures within the brain. However, for bipolar cautery devices where the poles are at a fixed distance apart from one another, the amount of energy for a given application can be too great for the intended target, thereby leading to undesirable collateral tissue damage.
In certain instances, carbonization build up occurs on the electrodes due to the heat created at the electrode tip; this carbonization is the result of the tissue being “cooked” onto the surface of the electrode. This buildup compromises the effectiveness of the energy delivery to accomplish coagulation or cauterization on the target tissue. As a result, higher levels of energy are required to be delivered to the electrodes to achieve coagulation of the bleeding vessel to overcome the resistance caused by the buildup. However, the energy levels of the non-buildup areas will then be too high, causing unnecessary thermal damage to surrounding tissues. Moreover, the conductive pathway may also be altered and flow in an unintended pathway, also causing unnecessary thermal damage to surrounding tissues.
It has been proposed to place sealed cooling channels in individual electrodes to reduce the thermal build up at the electrode tip in an attempt to prevent the tissue from being “cooked” on to the surface of the electrode which can lead to thermal damage to collateral tissue. Traditionally, however, these electrodes have a size that is relatively large to accommodate the cooling channels therein, and thus, this size requirement to achieve effective cooling precludes such electrodes from being applied to finer tip electrode designs. Indeed, these large sizes render such arrangements unsuitable for delicate microsurgical procedures, such as, for example, narrow corridor neurosurgical procedures for two reasons (1) the physical size of the electrode tips are too large to delicately handle and manage the vessel and (2) the surgical site is often only a few millimeters of a window to be operated through and the electrode tips preclude visualization of the surgical site.
Another issue that arises with the use of bipolar cautery devices is a phenomenon referred to as “sticktion.” Sticktion occurs when, after a vessel is coagulated and the electrodes are moved away from the coagulated/cauterized vessel, part of the vessel “sticks” to the electrodes. This often results in re-opening the vessel due to tearing, causing a rebleed of the vessel. To reduce “sticktion,” certain materials, such as silver, platinum, and gold, may be used with the electrodes. Such materials, however, have proven to be of limited effectiveness and of minimal benefit.
One proposed solution to reduce the heat at the electrode tips and thereby reduce tissue buildup, reduce sticktion, as well as minimize thermal damage to collateral tissues, is to provide an external saline drip into the surgical site. However, this approach often requires an additional person in the surgical field to deliver the fluid. Additionally, in minimally invasive microsurgical procedures, the surgical corridor and the subsequent target is relatively small, thus an external drip presents delivery challenges for the additional person and visibility challenges for the surgeon whom is using the coagulation device on the intended tissue to be coagulated due to too many instruments and hands in the surgical field simultaneously thereby precluding visualization at the surgical site. Moreover, it is challenging for the assistant providing the external drip to deliver the fluid to the electrode tips and the necessary location within the surgical site with any accuracy.
Another known bipolar coagulation device is bipolar forceps, whereby the two electrodes may be varied in distance from each other by the user. In some versions of these devices, fluid may be supplied through the forceps' legs of the device. To accommodate delivery of the fluid through the body of the forceps, the device must be relatively large which makes it unsuitable for microsurgical corridor approaches. Additionally, as the fluid delivery is proximal of the electrode tip, instead, this prior art design relies upon the fluid to flow along the body of each of the forceps legs to end up at the surgical site. Often in corridor microsurgical approaches the approach is not in a plane that is conducive to the fluid tracking along the leg of the forceps device. Accordingly, the fluid is not necessarily configured to be simultaneously delivered directly to the electrode tip and the surgical site.
Another issue that occurs in typical procedures using bi-polar devices is the variability of energy delivery at the distal tips due to tissue buildup. More specifically, tissue build-up on the electrode tips changes the resistance within the electrical circuit, i.e., the bipolar device and the attached bipolar generator. As a result, in a typical procedure, a surgeon will need to continually ask a surgical assistant to adjust, i.e, turn up, the output of the coagulation generator so as to compensate for the change in effectiveness of the bipolar device, as the procedure progresses. At some point during the procedure, the ineffectiveness and/or the inability of the bipolar device to deliver energy to effectively coagulate can no longer be accomplished by simple adjustment of the coagulation generator, or the surgeon becomes frustrated with the continuation needed adjustment of the coagulation generator. This frustration results in the surgeon having to remove the bipolar device from the surgical field and have a scrub nurse clean off the electrode tips. Moreover, while the electrode tips are being cleaned, the tissue/vessels that the coagulator was being applied to is still bleeding, causing risk to the patient. Alternatively, if additional bipolar coagulation devices are available, the scrub nurse may remove the bipolar device from the electrical cord attached to the coagulation generator, and replace the bipolar device with another bipolar device. The removal of the bipolar device from the surgical field and either cleaning or swapping it out with another bipolar device goes on repeatedly through an entire procedure.
However, once a surgeon has a clean bipolar device, the surgeon must then have a surgical assistant adjust the output of the coagulation generator again, i.e., turning the output down. As the clean bipolar device is used, the instruction sequence of “turning up and turning down” the output of the coagulation generator and swapping out the bipolar device for either cleaning or for a new bipolar device continues through the entire procedure. This process is inefficient, increases blood loss, which compromises patients' safety, and increases the length of a procedure.
Different vessels are different sizes. Thus, to maximize energy delivery to the intended vessel, it is desirable to straddle as close to the offending vessel as possible to minimize collateral energy dispersion. However, fixed parallel electrodes have no ability to easily accommodate different sized vessels, and often leads to digging into the tissue (and hence thermally damaging collateral tissue) to straddle the vessel.
Currently, bipolar devices also cause line of sight issues, especially during microsurgical procedures which also require working down a narrow corridor. More specifically, the electrode ends of the bipolar of are not visible in conjunction with the area of interest when the device is placed down a corridor, as the electrode shafts and/or the handle of the device or even the user's own hand blocks the view. Bayonet designs have been employed to address the needs of the microscopic procedures but these are of limited effectiveness in narrow corridor microsurgical approaches.
Another issue with currently available bipolar coagulation devices (as well as monopolar devices), is the ability to control visibility within the surgical field to identify an active bleeder and address the bleeder which is of unknown origin. What is needed is a single device which provides the ability to irrigate the entire field to push the blood away from a suspected bleeder location so as the user may clearly see the surgical field so as to locate the bleeder, as well as suction the excess fluid from the surgical field so as to visually clear the field to enable the user to coagulate the offending vessel while minimizing any collateral tissue damage during coagulation/cautery of the vessel.